Non ipv4 advertising peer causes BGP session flaps

Non ipv4 advertising peer causes BGP session flaps

During the session establishment phase, if a peer
doesn't advertise ipv4-unicast, controller
automatically adds ipv4-unicast as supported
family for the session to support classic BGP
sessions.

Currently, we are adding Ipv4 family in the
BGPPeer but not updating AdjRibInWriter which
causes the BGP session to not recover from
session flap. Patch fixes this issue by adding
ipv4 support before updating AdjRibInWriter.

JIRA: BGPCEP-910
Change-Id: I669104a17d603e0494f9ac7090a8fd671f67a3a5
Signed-off-by: Vikram Singh Kalakoti <vikramskalakoti@gmail.com>
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit f54f4bd31f5ceb0a15edacb9b2884a63a21cb52d)